Radial lip seals or radial contact seals are used to seal a shaft's circumferential surface by engagement of a lip with the surface to be sealed. In some cases, helical grooves in the engaging surface of the seal are provided to respond to shaft rotation by pumping the oil or other fluid back toward the oil sump to minimize leakage.
In order to provide an adequate seal, the radial lip seal must be installed so that the lip is angled axially inward toward the sump and stretched over the shaft with the helical grooves engaging the circumferential surface. However, during installation it is possible for the radial lip to be folded (flipped) over to at least a partially extend outward away from the oil sump with the back of the lip engaging the shaft. In this condition, the smooth back of the lip may provide a minimal leak path so that a low pressure air test may not detect the flipped seal.
A method of increasing the leak path of a flipped seal is desired so that a flipped seal can be detected with a low pressure air test.